IS 13360 (Part 8/See 11): 1999 ISO 6252:1992 a=yP-lll whvm?mdk%il=l@hTIFft) wm-a=l=l sil'?fm=il­ Jrfima W-R Indian Standard PLASTICS -- METHODS OF TESTING PART 8 PERMANENCWCHEMICAL PROPERTIES Section 11 Determination of Environmental Stress Cracking (ESC) -- Constant-Tensile Stress Method ? . ICS 83.080; 19.060 @ BIS 1999 BUREAU OF NEW INDIAN DELHI STANDARDS MANAK BHAVAN, 9 BAHADUR SHAH ZAFAR MARG 110002 April 1999 Price Group 4 Methods of Test for Plastics Sectional Committee, PCD 23 NATIONAL FOREWORD This Indian Standard ( Part WSec 11 ) which is identical with ISO 6252 : 1992 `Plastics -- Determination of environmental stress cracking ( ESC ) -- Constant-tensile-stress method' issued by the International Organization for Standardization ( ISO ) was adopted by the Bureau of Indian Standards on the recommendation of Methods of Test for Plastics Sectional Committee and approval of the Petroleum, Coal and Related Products Division Council. The text of ISO standard has been approved as suitable for publication as Indian Standard without deviations. Certain conventions are, however, not identical to those used in Indian Standards. Attention is particularly drawn to the following: a) Wherever the words `International Standard' appear referring to this standard, they should be read as `Indian Standard'. b) Comma (,) has been used as a decimal marker while in Indian Standards, the current practice is to use a point (.) as the decimal marker. In this adopted standard, reference appears to certain International Standards for which Indian Standards also exist. The corresponding Indian Standards which are to be substituted in their place are listed below along with their degree~f equivalence for the editions indicated: International Standard Corresponding Indian Standard Degree of Equivalence ISO and and and 150:1980 Raw, refined boiled linseed oil for paints varnishes -- Specification methods of test NH -- ISO 291 : 1997 Plastics -- Standard atmospheres for conditioning and testing ISO 293 : 1986 Plastics -- Compression moulding test specimens of thermoplastic materials ISO 294 : 1995 Plastics -- Injection moulding of test specimens of thermoplastic materials IS 196:1966 Atmospheric testing ( revised) conditions for Technically equivalent with minor deviations Technically equivalent IS 13360 ( Part 2/See 1 ) :1992 Plastics -- Methods of testing : Part 2 Sampling and preparation of test specimens, Section 1 Compression moulding test specimens of thermoplastic materials IS 8543 ( Part 3/See 2 ) :1978 Methods of testing plastics : Part 3 Preparation of test specimens, Section 2 Injection moulded test specimens Not technically equivalent in all respects. However, this Indian Standard will be considered for revision to align it with ISO as and when the revised version of ISO 294:1995 is available Technically equivalent ISO 527:1966 Plastics-- Determination of tensile properties IS 8543 ( Part 4/See 1 ) :1984 Plastics -- Methods of testing : Part 4 Short term mechanical properties, Section 1 Determination of tensile ~ro~erties . . ( Continued on third cover) IS 13360 (Part 8/Ssoll ISO 6252:1992 ):1999 Indian Standard PLASTICS -- METHODS OF TESTING PART 8 PERMANENCE/CHEMICAL PROPERTIES Section 11 Determination of Environmental Stress Cracldng (ESC) -- Constent-Tensile Stress Method .. 1 scope lSO/R 527:1966, Plastics ­ Determination properties. ISO 899:1981, P/asfics creep. ­ Detr?rminafion of tensile This International Standard specifies methods for the determination of environmental stress cracking (ESC) of plastics when they are subjected to a constant tensile force in the presence of chemical agents. it is applicable to test specimens prepared by moulding andlor machining and can be used both for the assessment of ESC of plastics materials exposed to different environments, and for the determination of ESC of different plastics materials exposed to a specific environment. NOTE 1 Methods for the determination of environmental stress cracking by means of a constant-strain test are specified in ISO 4599 and 1S0 4600. of tensi/e ISO 2557-1:1989, P/astics ­ Amorphous thermoplastics ­ Preparation of test specimens with a specitied maximum reversion -- Part 1."Bars. ISO 2818:1980, Phwtics ­ Preparation mens by machining. ISO 3167:1983, Plastics ­ Preparation multipurpose test specimens. of test speci- and use of ISO 4599:1986, Plastics ­ Determination of resistance to environmental stress cracking (ESC) -- Bent strip method. ISO 4600:1992, F'/astics ­ vironmental stress cracking pression method. Determination of en(ESC) ­ Ba/1 or pin im- . 2 Normative references The following standards contain provisions which, through reference in this text, constitute provisions of this International Standard. At the time of publication, the editions indicated were valid. All standards are subject to revision, and parties to agreements based on this International Standard are encouraged to investigate the possibility of applying the most recent editions of the standards indicated below. Members of IEC and ISO maintain registers of currently valid International Standards. ISO 150:1980, Raw, refined and boiled linseed oil for paints end varnishes ­ Specifications and methods of test. ISO 291:1977, Plastics -- Standard conditioning and testing. atmospheres for 3 Principle A test specimen is subjected to a constant tensile force, corresponding to a stress lower than that at yield, while immersed in a specified environment at the temperature selected for testing. The time andlor stress at which the specimen breaks is recorded. The environmental stress cracking of the test specimens is determined by one of the following methods (A, B or C), depending upon the time to rupture: ­ Method A: Determination of the tensile stress leading to rupture at 100 h. This stress is obtained by interpolation of the graph of time to rupture versus applied tensile stress. Method B: Determination of the time to rupture under a specified tensile stress. This method is used when the time to rupture exceeds 100 h. ISO 293:1986, Plastics ­ Compression specimens of thermoplastic materials. ISO 294:1 g75, P/astics ­ specimens of thermoplastic moulding test ­ Injection tnoulding materials. test 1 IS 13360 (Part 8/Secll ISO 6252:1992 ):1999 ­ Method C: Determination of the Iensile stress versus time to rupture curve up to an agreed time. are desired, the method either the agent which will be in contact with the material in the expected application or a reference product agreed upon between the interested parties. NOTE 3 a) Examples of reference products are: quality (ethylene- NOTE 2 If creep measurements outlined in ISO 899 is followed. 95 0/6 (V/V) ethanol ­ pharmaceutical 4 Apparatus b) solution of nonylphenoxy-poly a 1 0/0 (mlm) oxy)ethanol !) in distilled water; refined linseed oil (see ISO 150). 4.1 Testing device, allowing test specimens to be submitted simultaneously to a tensile stress and to the chemical environment. If the chemical is a liquid at the test temperature, test specimen shall be completely immersed in it is highly viscous at the test temperature, specimens may be covered with a coating of agent at least 2 mm thick (see clause 5). the it. If the the c) 6 6.1 Conditioning Conditioning and test conditions The parts of the device that come into contact with the chemical shall be made of an inert material, for example stainless steel. The constant tensile stress may be applied with weights (figures 1 and 2 are schematic diagrams of suitable apparatus). The force z;, all be accurate to + 1 O/O. Care shall be taken to ensure that there is no loss of stress in the system, for example by friction. If the testing device has several test stations, means shall be provided to prevent the vibration occurring through failure at one station from being transmitted to the whole system. Care shall be taken that the specimens are subjected only to forces parallel to their longitudinal axis, and not to bending or twisting forces. bath or room, allowing 4,2 Temperature-controlled the test system to be maintained at (23 ~ 1) "C or at a higher test temperature up to 105 `C to within + 0,5 `C (see clause 6). timer, as shown schematically in 4.3 Automatic figure 2, to measure the time to rupture of each specimen to 1 0/0 or better. Unless otherwise agreed between the interested parties, the test specimens shall be conditioned before testing for at ieast 24 h at (23 + 2) `C and (50 A 5) "A relative humidity (see ISO 291). 6.2 Test temperature The preferred test temperatures are (23 + 1) "C and (55 ~ 0,5) "C. If required, other temperatures may be used, preferably selected from the following: (40 * 0,5) "c (70 * 0,5) `c (85 + 0,5) "C (loo f 0,5) `c or as agreed upon by the interested parties. 7 7.1 Test stress Maximum permissible stress The stress applied to the test specimen during the test shall be less than the tensile stress at yield of the material at the temperature of the test. NOTE 4 As a general guide, the stress that produces an elongation of 2 0/0 after 1 h can be taken as the maximum permissible stress. This stress can be determined by preliminary tests using several different stresses. 4.4 Equipment for the preparation of test specimens by moulding (see ISO 293 and ISO 294), machining (see ISO 2818) or die cutting. 5 Chemical environment 7.2 Method A The chemical environment used for the test shall be that specified in the relevant International Standard for the material tested. If nothing is specified, use Determine the tensile stress required to cause rupture after 100 h by applying a series of stresses, the maximum stress being as defined in 7.1. 1) This detergent is an example of a suitable product available of users of this International Standard and does not constitute commercially. This information is given for the convenience an endorsement by ISO of this product. 2 IS 13360 (Part 8/Secll ISO 6252:1992 ):1999 ? Key 1 2 3 4 5 Cover support Upper clamp Lower clamp Test specimen Chetnical environment Glass container Vibration damping basa %PPOrt Microstitch connected to timer --_ .-- -- -MkL q ----.\\. @ 6 7 8 9 ­-----k\._..4..- c r Q . . . . . . . . . . . . . . . . ,... ,... ,>.. ~J ,... .. . . . . . . . . . . . . . . . . . . . . . . . . ...... ,... `.".".".".".".. .... ... ... ... . . . . . ......... ................. ,... . . . . . . . . . . . . . . .............................. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . I . . . . . . . . . . . . . . . . . . . . . . . . . -- --. .--= . J --._ _ --. -- .-- W- , .-- .-- 3 6 I 10 Weights 91 I L I Figure 1 ­ One type of apparatus for measuring fracture under constant stress 3 Is 13380 (Part8/secll):199fJ 1S0 6252:1992 2 3 1 Key 1 2 Balance Frictionlese bearing, or knife edge Wire attachment point Wire Circulation of temperature-controlled liquid Clampa Teat specimen Chemical environment Waighta Switch controlling timer IF . . . . . . 3 4 5 6 7 6 9 6/ -. k---- 6--__ 8/ .-- b ,.. . i . . . #j. .--. -- Figure 1= . . . . 10 ~r -1 5 i 2 ­ Balance type of apparatus 11 Timer d 1 10 ---q-@with 2:1 amplification of 11 load 7.3 Method B Determine the time to rupture under a single stress as agreed between the interested parties, but not higher than the maximum permissible stress defined in 7.1. 7.4 The preferred thickness is (2 t 0,2) mm, but when the test specimens are prepared from products the thickness may be that of the product. ARernatively, a type 1 specimen 3 mm to 4 mm thick may be used. Attention specified is drawn to the multipurpose in ISO 3167. specimen Method C Determine the times to rupture for a series of stresses. The loads shall be chosen in accordance with 9.7. 8 8.2 Number Test specimens Shape and dimensions 8.1 At least five specimens shall be tested at each tensile stress in the case of methods A and B and at least two specimens for each stress in the case of method C. If the material is thought to be anisotropic, two sets of specimens shall be used, one set cut at right angles to the other in two of the principal directions. Use the type 1 specimen specified in lSO/F? 527, with all dimensions scaled down by a ratio of 1:2 as shown in figure 3. 4 IS 13360 (Part 8/Secll ISO 6252:1992 ):1999 -u--L\ k Key A B Overell length, minimum: 75mm Wkfthatends: 10mm * 0,5mm L-J--l c D E F G H Length of narrow, parallal-sided poRion: 30mm Wdthofnarrow, parallel-sided portion: 5mm * 0,5mm + 0,5mm Radius, minimum: 30mm Thickness: 2 mm + 0,2 mm Distance between gauga marks: 25 mm Initial distance between grips: 57 mm Figure 3 ­ lSO/R 527 Type 1 specimen (scaled down 1:2) 8.3 Preparation The s~ecimens shall be nre~ared in accordance with tne appropriate International Standard. If nothing is stated, specimens shall be machined from sheet or from products by the methods specified in ISO 2818. If sheets are prepared from moulding materials, they shall be moulded in accordance w-ith the relevan-t material specification or as agreed between the interested parties. Specimens shall not be cut with a die unless machining is impossible, for example with soft materials. If specimens dures shall ISO 294. NOTES 5 Environmental stress cracking of a specimen is influenced not only by the material, but also by the method of preparation. Materials should only be compared using specimens prepared in a similar manner and in the same state. Attention is drawn to ISO 2557-1 nation of level of shrinkage for the determi- 6 Injection-moulded test specimens often have a considerable amount of orientation. If the load is applied parallel to the direction of injection, the time to rupture may be significantly longer than in the transverse direction. If the specimens are anisotropic, it may be useful to carry out tests with the load applied in different directions relative to the direction of injection. 9 Procedure are prepared by mouiding, the procebe in accordance with ISO 293 or 9.1 Measure, to the nearest 0,01 mm, the thickness and the width of the central, parallel-sided portion of each specimen and calculate the force F, in newtons, to be applied, using the equation F'= r7"A where c is the stress, in megapascals, the test (as described in 7.1); selected for A is the area of cross-section, in square millimetres, of the central, parallel-sided portion of the specimen. 5 IS 13360( Part 6/See 11 ): 1999 ISO 6252:1992 NOTE 7 To determine commended a) the cross-sectional area it is re- the load is applied (t= O). Record the time to rupture for each specimen and the type of break (brittle or ductile). If a liquid chemical environment is used, it shall be renewed with liquid from the same batch for each test specimen (apparatus with one station) or each group of test specimens (apparatus with several stations). to measure the thickness at each end of the parallelsided portion and take the minimum value; to measure the width of each face at each end of the parallel-sided portion and to take the mean value. b) 9.2 Heat the temperature-controlled (4.2) to the selected test temperature. bath or room 9.3 Insert the specimens in the clamps of the testing device (4.1) and immerse them in the test liquid or coat them with the chemical. Suitable clamp arrangements are shown schematically in figure4. 9.4 men, time case After 15 rein, apply the load F to each speciwithout shock, in such a way that the loading is preferably between 3 s and 5 s and in any less than 10 s. Start the timer (4.3) as soon as 9.5 When method A is used, perform the test with a series of tensile stresses up to and including the maximum permissible stress as defined in 7.1. NOTE8 The f 00 h stress is obtained by interpolation of a stress versus log time plot (see 10.1), If the logarithm of the arithmetic mean of the times to rupture is used, the A more conservative longer times are overemphasized. assessment of the times to rupture can be obtained by calculating the mean of the logarithms of the measured times to rupture, i.e. the geometric mean. A E+lFmiz V' c I d- Key A B Specimen fixing plate Clamping jaw for the braid Figure 4 ­ Example of suitable clamp arrangement 6 IS 13360 (Part 8/See 11 ): 1999 ISO 6252:1992 9.6 When method B is used, perform the test using a specified or agreed stress not higher than the maximum permissible stress as defined in 7.1 (see 7.3). [f no break occurs after 1000 h, terminate the test and record this fact in the test report. 9.7 When method C is used, perform the test using a series of stresses. The loads shall be chosen so as to fall within the range from 10 0/0to 90 `A of the short-time tensile strength of the material and shall be selected from the following numbers: 1; 2; 3; 5; 7,5; 10 and their decimal multiples. 9.8 If required, carry out a parallel series of tests, as described in 9.5 or 9.6, in air or another reference environment. of the variety of plastics materials and environmental conditions. These methods may not be suitable for use in the event of disputed results as long as no precision data are available. 12 Test report The test report shall include the following particulars: a) a reference b) all details tested; c) the chemical to this International necessary to Standard; the material identify environment used; 10 10.1 Expression Method A of results d) the test temperature; e) the number of specimens tested (if applicable, in each direction of anisotropy) and their width and thickness; 9 the procedure used for preparation of the specimens and, whenever possible, the elapsed time between their preparation and the beginning of testing; Calculate the arithmetic mean and the standard deviation of the measured times to rupture. Plot the logarithm of the mean, in hours, as abscissa versus tensile stress, in megapascals, as ordinate and determine by interpolation the stress corresponding to a time to rupture of 100 h. 10.2 Method 8 9) the state of the specimens; h) the conditioning duration and atmosphere; Calculate the arithmetic mean of the times to rupture, in hours, obtained from the five specimens and the standard deviation. For some purposes, the geometric, rather than NOTE 9 tbe arithmetic, mean may be found useful because the logarithms of the times to rupture often show a better Gaussian distribution than the times to rupture. i) j) the stresses applied; the times to rupture, individual and mean values and standard deviations (methods A and B only), for each stress applied. If no rupture occurs after 1000 h under the maximum permissible stress as defined in 7.1, report that fact; to 100 h 10.3 Method C k) for method A, the stress corresponding time to rupture; 1) the type of break, i.e. brittle or ductile; Calculate the arithmetic mean of the times to rupture for each stress used. Plot the logarithm of each mean time to rupture in hours (as abscissae) versus tensile stress in megapascals (as ordinates). 11 Precision m) any operational details not specified in this international Standard, and any circumstance liable to have influenced the results; n) results from parallel series of tests in air or another reference environment, if used. The precision of these methods is not known because inter-laboratory data are not available in view IS 13360( Part 6/See 11 ): 1999 ISO 6252:1992 Annex (informative) A Examples of stresses to be applied Type of plastic Temperature Maximum stress to be applied "c Po\yamide 66 55 55 23 55 55 M Pa 30 40 50 21 4 to 7 depending on the molecular mass Poiycarbonate Polycarbonate PVC (unplasticized) Polyethylene (high density) Poly(methyl Poly(methyl methacrylate) methacrylate) 55 23 55 25 40 28 Poly(oxymethylene) NOTE 10 These Yalues are given ecular mass of the polymer tested. for information only. The maximum permissible stress is dependent upon the mol- 8 ( Lonrmuea rrom secorm cover] Standard Corresponding Indian Standard Degree of Equivalence International ISO 899-1 :1993 Plastics -- Determination of creep behaviour -- Part 1 : Tensile creep ISO 2557-1 :1989 Plastics -- Amorphous thermoplastics -- Preparation of test specimens with a specified maximum reversion -- Part 1: Bars ISO 2818:1994 Plastics -- Preparation of test specimens by machining Nil Nil -- IS 13360 ( Part 2/See 4 ) :1998 Plastic -- Methods of testing : Part 2 Sampling and preparation of test specimens, Section 4 Preparation of test specimens by machining ( first revision) IS 13360( Part 2/See 5 ) :1997 Plastics -- Methods of testing : Part 2 Sampling and preparation of test specimens, Section 5 Multipurpose test specimens IS 13360( Part 8/See 9 ) :1997 Plastics -- Methods of testing : Part 8 Permanence/ chemical properties, Section 9 Determination of resistance to environmental stress cracking (ESC) -- Bent .strip method IS 13360( Part 8/See 10) :1998 Plastics -- Methods of testing : Part 8 Permanence/ chemical properties, Section 10 Determination of environmental stress cracking (ESC) ­ Ball or pin impression method Identical ISO 3167 : 1993 Plastics -- Multipurpose test specimens do 1s0 4599 : 1986 Plastics -- Determination of resistance to environmental stress cracking (ESC) ­ Bent strip method do ISO 4600 : 1992 Plastics -- Determination of environmental stress cracking ( ESC ) -- Ball or pin impression method do In the case of ISO 150, ISO 899-1 and ISO 2557-1, the Technical Committee responsible for the preparation of this standard has reviewed its contents and has decided that they are acceptable for use in conjunction with this standard. For tropical countries like India, the standard temperature and the relative humidity shall be taken as 27* 2°C and 65 * 5 percent respectively. In reporting the results of a test or analysis made in accordance with this standard, if the final value, observed or calculated, is to be rounded off, it shall be done in accordance with IS 2:1960 `Rules for rounding off numerical values ( revised)'. 1986 to promote harmonious BIS is a statutory institution established under the Bureau oflndian StandardsAct, development of the activities of standardization, marking and quality certification of goods and attending to connected matters in the country. Copyright BIS has the copyright of all its publications. NOpart of these publications maybe reproduced in any form without the prior permission in writing of BIS. This does not preclude the free use, in the course of implementing the standard, of necessary details, such as symbols and sizes, type or grade designations. 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